The present invention relates to a search radar system provided with at least one search radar device having a primary antenna and at least one secondary radar device having an SSR/IFF antenna, which radar devices independently of each other provide plot messages from which signals are derived that are suitable for presentation on a radar display.
In such search radar systems, provided with one search radar device having a primary antenna and one secondary radar device having an SSF/IFF antenna, it is common that the SSR/IFF antenna is fitted on top of the primary antenna and is aligned in azimuth with and synchronously rotatable with the primary antenna. The secondary radar device only serves as a support for the search radar: it supplements the information obtained by the search radar apparatus with, for example, an identity code of a target. The plot data obtained by the two radar devices are combined and presented as one picture on the radar display.
If such a search radar system is used for Air Traffic Control purposes, and particularly for the guidance of air traffic approaching the airport, it is favourable to maintain a relatively high antenna rotation rate, thus achieving a high refreshment rate of the received data on a radar display. On the other hand, it is also favourable to keep the antenna rotation rate relatively low because in that way the demands on the antenna drive mechanism of the search radar system are lower, and the number of hits per scan can become higher, resulting in a better MTI performance.